Computing devices have become integral tools used in a wide variety of different applications, such as in finance and commercial transactions, computer-aided design and manufacturing, health care, telecommunication, education, etc. Computing devices are finding new applications as a result of advances in hardware technology and rapid development in software technology. Furthermore, the functionality of a computing device is dramatically enhanced by coupling these types of stand-alone devices together to form a networking environment. Within a networking environment, computing device users may readily exchange files, share information stored on a common database, pool resources, and communicate via electronic mail (e-mail) and video teleconferencing.
Conventional computing devices provide several ways for enabling a user to input a choice or a selection. For example, a user can use one or more keys of an alphanumeric keyboard communicatively connected to the computing device in order to indicate a choice or selection. Additionally, a user can use a cursor control device communicatively connected to the computing device to indicate a choice. Also, a user can use a microphone communicatively connected to the computing device to audibly indicate a particular selection. Moreover, touch sensing technology can be used to provide an input selection to a computing device or other electronic device.
Within the broad category of touch sensing technology there exist capacitive sensing touch sensors. Among conventional capacitive touch sensors, there are different sensing technologies. For example, one sensing technology involves the use of sensing electrodes formed in triangular shapes wherein the direction of each triangle point alternates. However, there are disadvantages associated with this technique. For instance, one of the disadvantages is that as a finger (or object) moves towards the wide end of a first triangular shaped electrode and the narrow point of a second triangular shaped electrode, the narrow point electrode does not provide a quality signal because of its inherent signal-to-noise ratio. As such, this can be referred to as sensing geometry that induces signal-to-noise ratio concerns.
Another sensing technology uses a grid of conductive elements that cross over one another. While this design offers ease of signal interpretation, it also has the disadvantage of higher manufacturing cost.
Another factor to consider in the design of a capacitive sensing apparatus is that the sensed position of a finger or object relative to the touch sensor should be unambiguous. That is, for example, the response of the sensing apparatus to a finger at any location on a touch sensor should be different from the response at other locations on the touch sensor.
Thus, a capacitive sensing apparatus that addresses one or more of the above-mentioned issues would be advantageous.